Method, apparatus and system for processing very-high-speed random access

ABSTRACT

A method for processing very-high-speed random access includes: selecting a Zadoff-Chu (ZC) sequence group according to a cell type and a first cyclic shift parameter Ncs, and setting N detection windows for each ZC sequence in the ZC sequence group, where N≥5; sending the cell type, a second Ncs, and the ZC sequence group to a user equipment (UE); receiving a random access signal sent by the UE, and obtaining the random access sequence from the random access signal; performing correlation processing on the random access sequence with each ZC sequence in the ZC sequence group, detecting a valid peak value in the N detection windows of each ZC sequence, and determining an estimated value of a round trip delay (RTD) according to the valid peak value, so that a UE in a very-high-speed scenario can normally access a network, thereby improving network access performance.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.16/026,830, filed Jul. 3, 2018, which is a continuation of U.S. patentapplication Ser. No. 15/601,703, filed May 22, 2017, now U.S. Pat. No.10,039,133, which is a continuation of U.S. patent application Ser. No.14/600,615, filed Jan. 20, 2015, now U.S. Pat. No. 9,674,872, which is acontinuation of International Application No. PCT/CN2013/076974, filedon Jun. 8, 2013, which claims priority to Chinese Patent Application No.201210278680.4, filed on Aug. 7, 2012. All of the afore-mentioned patentapplications are hereby incorporated by reference in their entireties.

TECHNICAL FIELD

The present disclosure relates to the field of mobile communicationssystems, and in particular, to a method, an apparatus and a system forprocessing very-high-speed random access.

BACKGROUND

In a Long Term Evolution (LTE) system, a random access channel (RACH) ismainly used for initial access of a user equipment (UE) and does notcarry any user data. A signal sent by a UE on an RACH is a preamblesequence, where the preamble sequence is a Zadoff-Chu sequence (ZCsequence). In the prior art, a Preamble may include two parts which area section of cyclic prefix (CP) with a length of T_(CP) and a section ofaccess sequence (SEQ) with a length of T_(SEQ). In addition, parametersettings of different formats of Preambles may be matched to differentcell radii, as shown in Table 1:

TABLE 1 Preamble sequence Maximum cell format No. T_(CP) T_(SEQ) radius(km) 0 3168 · T_(s)   24576 · T_(s) Approximately 14.6 1 21024 · T_(s)   24576 · T_(s) Approximately 77.3 2 6240 · T_(s) 2 · 24576 · T_(s)Approximately 29.6 3 21024 · T_(s)  2 · 24576 · T_(s) Approximately 1004  448 · T_(s)    4096 · T_(s) Approximately 1.4

where T_(s) is a basic time unit in an LTE protocol, andT_(s)=1/(15000×2048)s.

In the prior art, a 0-15 km/h low speed scenario is optimized by the LTEsystem, so that relatively high performance is still achieved in a15-120 km/h high speed movement scenario, and connection can still bemaintained in a 120-350 km/h high speed movement scenario. In anexisting LTE protocol, two cell configurations, an unrestricted cellconfiguration and a restricted cell configuration, are supported, wherean unrestricted cell is applied to a low frequency deviation scenario(for example, the frequency deviation is less than 600 Hz), and arestricted cell is applied to a high frequency deviation scenario (forexample, the frequency deviation is greater than 600 Hz). With regard toa restricted cell, when a random access signal sent by a UE uses a ZCsequence as a random access sequence, an evolved base station (evolvedNode B, NodeB or eNB or e-NodeB) can ensure correct detection of a roundtrip delay (RTD) within a frequency deviation range where

$\left\lbrack {{- \frac{3*\Delta \; f_{RA}}{2}},\frac{3*\Delta \; f_{RA}}{2}} \right\rbrack,$

Δf_(RA) represents a subcarrier spacing of the random access channel,and the UE adjusts a timing advance (TA) according to the RTD, therebyadjusting message sending timing and ensuring that the UE can normallyaccess a network.

With the development of communications technologies and increasedcommunications requirements of users, operators come up withrequirements for coverage in very-high-speed movement scenarios and highfrequency band high-speed railway scenarios. In the two types ofscenarios, a frequency deviation of the random access signal is larger,which is

$\left\lbrack {{- \frac{W*\Delta \; f_{RA}}{2}},\frac{W*\Delta \; f_{RA}}{2}} \right\rbrack,$

where W≥5. It is very difficult for an eNB to ensure correctness of RTDdetection under a high frequency deviation. As a result, it is verydifficult to ensure that a UE normally accesses a network, which affectsaccess performance of the network.

SUMMARY

Embodiments of the present invention provide a method, an apparatus anda system for processing very-high-speed random access, so that a userequipment in a very-high-speed movement scenario can normally access anetwork, so as to improve access performance of the network.

One aspect of the present invention provides a method for processingvery-high-speed random access, including: selecting a ZC sequence groupaccording to a cell type and a first cyclic shift parameter Ncs, andsetting N detection windows for each ZC sequence in the ZC sequencegroup, where N≥5; sending the cell type, a second Ncs, and the ZCsequence group to a user equipment UE, so that the UE selects a randomaccess sequence from the ZC sequence group; receiving a random accesssignal sent by the UE, and obtaining the random access sequence from therandom access signal; and performing correlation processing on therandom access sequence with each ZC sequence in the ZC sequence group,detecting a valid peak value in the N detection windows of each ZCsequence, and determining an estimated value of a round trip delay RTDaccording to the valid peak value.

Another aspect of the present invention provides an apparatus forprocessing very-high-speed random access, including: a selecting unit,configured to select a ZC sequence group according to a cell type and afirst cyclic shift parameter Ncs; a setting unit, configured to set Ndetection windows for each ZC sequence in the ZC sequence group selectedby the selecting unit, where N≥5; a sending unit, configured to send thecell type, a second Ncs, and the ZC sequence group selected by theselecting unit to a user equipment UE, so that the UE selects a randomaccess sequence from the ZC sequence group; a receiving unit, configuredto receive a random access signal sent by the UE and obtain the randomaccess sequence from the random access signal; and a detecting unit,configured to perform correlation processing on the random accesssequence obtained by the receiving unit with each ZC sequence in the ZCsequence group, detect a valid peak value in the N detection windows setby the setting unit for each ZC sequence, and determine an estimatedvalue of a round trip delay RTD according to the valid peak value.

It can be known from the above technical solutions that, by using theembodiments of the present invention, a ZC sequence group is selectedaccording to a cell type and a first cyclic shift parameter Ncs, Ndetection windows are set for each ZC sequence in the ZC sequence group,where N≥5, and an estimated value of the RTD is determined according toa valid peak value detected in the N detection windows of each ZCsequence. In this way, a problem that an RTD of a random access signalcannot be correctly detected in a very-high-speed scenario is solved, itis ensured that a user equipment moving at a very high speed cancorrectly adjust a TA value according to a detected RTD, and thereforemessage sending timing is correctly adjusted, so that the user equipmentin a very-high-speed scenario can normally access a network, therebyimproving access performance of the network.

BRIEF DESCRIPTION OF DRAWINGS

To describe the technical solutions in the embodiments of the presentinvention more clearly, the following briefly introduces theaccompanying drawings required for describing the embodiments.Apparently, the accompanying drawings in the following description showsome embodiments of the present invention, and persons of ordinary skillin the art may still derive other drawings from these accompanyingdrawings without creative efforts.

FIG. 1 is a flowchart of a method for processing very-high-speed randomaccess according to an embodiment of the present invention;

FIG. 2 is a flowchart of another method for processing very-high-speedrandom access according to an embodiment of the present invention;

FIG. 3 is a schematic diagram illustrating changing of a valid peakvalue with frequency deviations in detection windows according to anembodiment of the present invention;

FIG. 4 is a flowchart of another method for processing very-high-speedrandom access according to an embodiment of the present invention;

FIG. 5 is a flowchart of still another method for processingvery-high-speed random access according to an embodiment of the presentinvention;

FIG. 6 is a schematic diagram of a position relation between a validpeak value and an overlap between detection windows according to anembodiment of the present invention; and

FIG. 7 is a schematic structural diagram of an apparatus for processingvery-high-speed random access according to an embodiment of the presentinvention.

DESCRIPTION OF EMBODIMENTS

The following clearly describes the technical solutions in theembodiments of the present invention with reference to the accompanyingdrawings in the embodiments of the present invention. Apparently, thedescribed embodiments are merely a part rather than all of theembodiments of the present invention. All other embodiments obtained bypersons of ordinary skill in the art based on the embodiments of thepresent invention without creative efforts shall fall within theprotection scope of the present invention.

As shown in FIG. 1, a method for processing very-high-speed randomaccess according to an embodiment of the present invention isspecifically described as follows:

101. Select a ZC sequence group according to a cell type and a firstcyclic shift parameter Ncs, and set N detection windows for each ZCsequence in the ZC sequence group, where N≥5.

The cell type includes an unrestricted cell and a restricted cell, andmay be configured according to an application scenario. For example, thecell type may be configured to unrestricted cell for a low speedscenario, and configured to restricted cell for a high speed scenario.

The first Ncs is used to represent a cell coverage range, that is, acell coverage radius. The larger the first Ncs is, the larger the cellcoverage range is. Configuration of the first Ncs belongs to the priorart, and therefore is not described herein any further.

The ZC sequence group includes M ZC root sequences, where M≤64. In the3GPP TS 36.211 protocol, 838 ZC root sequences are defined totally. TheZC sequence group may include 64 ZC root sequences at most.

The setting N detection windows for each ZC sequence in the ZC sequencegroup may specifically include the following steps.

First, obtain a du_(HT) value of the i^(th) ZC sequence in the ZCsequence group.

The du_(HT) value of the i^(th) ZC sequence refers to a shift of amirror image peak in a power delay profile PDP of the i^(th) ZC sequencerelative to an RTD when a frequency deviation is

${\pm \frac{1}{T_{SEQ}}},$

where T_(SEQ) is a time duration occupied by the i^(th) ZC sequence anda value of i is any integer in [1, M].

The du_(HT) values may be obtained by using a manner A1 or a manner A2.

In the manner A1, the value is obtained by calculation according toFormula 1, which is detailed as follows:

$\begin{matrix}{{du}_{HT} = \left\{ \begin{matrix}{- p} & {0 \leq p < {N_{ZC}/2}} \\{N_{ZC} - p} & {else}\end{matrix} \right.} & \left( {{Formula}\mspace{14mu} 1} \right)\end{matrix}$

where P is a minimum non-negative integer when (p·u) mod N_(zc)=1, u isa physical root sequence number of the ZC sequence, and Nzc is a lengthof the ZC sequence, where the Nzc may be 839 or 139. When Nzc is a fixedvalue, p is decided by a value of u. Then, according to the aboveFormula 1, the du_(HT) is decided by the value of u.

For example, if Nzc=839, when the physical root sequence number u=3,(p·3)mod 839=1, p=280, and du_(HT)=280 can be obtained according toFormula 1; when the physical root sequence number u=836 (p·836)mod839=1, p=1119, and, du_(HT)=280 can be obtained according to Formula 1.

In the manner A2, the value is obtained by querying Table 2 or Table 3.

Table 2 lists du_(HT)(u) values when Nzc=839, where u=1, . . . 419. Whenu=420, . . . , 838, du_(HT)(u) values can be obtained using a formuladu_(HT)(Nzc−u)=−du_(HT)(u), u=1, . . . , 419. For example, when thephysical root sequence number u=3, it can be obtained by querying thetable that du_(HT)=−280; when u=450, Nzc−u=839−450=389. Let u′=389, andthen du_(HT)(Nzc−u′)=−du_(HT)(u′)=−du_(HT)(u′)=−du_(HT)(389)=110.

TABLE 2 Values of du_(HT) when N_(ZC) = 839 u du_(HT) 1 −1 2 419 3 −2804 −210 5 −168 6 −140 7 −120 8 −105 9 −373 10 −84 11 305 12 −70 13 129 14−60 15 −56 16 367 17 148 18 233 19 −265 20 −42 21 −40 22 −267 23 −73 24−35 25 302 26 −355 27 −404 28 −30 29 405 30 −28 31 −406 32 −236 33 −17834 74 35 −24 36 −303 37 68 38 287 39 43 40 −21 41 266 42 −20 43 39 44286 45 261 46 383 47 357 48 402 49 −137 50 151 51 329 52 242 53 −95 54−202 55 61 56 −15 57 −368 58 −217 59 −128 60 −14 61 55 62 −203 63 −29364 −118 65 −142 66 −89 67 288 68 37 69 −304 70 −12 71 −130 72 268 73 −2374 34 75 −179 76 −276 77 −316 78 −398 79 −308 80 409 81 145 82 133 83374 84 −10 85 −306 86 −400 87 135 88 143 89 −66 90 −289 91 378 92 −22893 −415 94 −241 95 −53 96 201 97 −173 98 351 99 −339 100 −344 101 −108102 −255 103 −391 104 121 105 −8 106 372 107 345 108 −101 109 254 110−389 111 −257 112 412 113 −297 114 −184 115 321 116 311 117 294 118 −64119 141 120 −7 121 104 122 −392 123 −191 124 318 125 396 126 273 127 218128 −59 129 13 130 −71 131 −269 132 375 133 82 134 144 135 87 136 −401137 −49 138 −152 139 169 140 −6 141 119 142 −65 143 88 144 134 145 81146 408 147 234 148 17 149 366 150 330 151 50 152 −138 153 −170 154 −158155 −249 156 −199 157 171 158 −154 159 248 160 −215 161 −370 162 −347163 175 164 −353 165 300 166 187 167 211 168 −5 169 139 170 −153 171 157172 −200 173 −97 174 −352 175 163 176 −348 177 237 178 −33 179 −75 180275 181 394 182 189 183 298 184 −114 185 −322 186 212 187 166 188 299189 182 190 393 191 −123 192 −319 193 −313 194 333 195 −327 196 −244 197362 198 250 199 −156 200 −172 201 96 202 −54 203 −62 204 292 205 221 206224 207 −381 208 −359 209 281 210 −4 211 167 212 186 213 −323 214 −247215 −160 216 369 217 −58 218 127 219 272 220 225 221 205 222 291 223−380 224 206 225 220 226 271 227 −377 228 −92 229 414 230 −259 231 −385232 −264 233 18 234 147 235 407 236 −32 237 177 238 −349 239 337 240 416241 −94 242 52 243 328 244 −196 245 −363 246 324 247 −214 248 159 249−155 250 198 251 361 252 −283 253 −388 254 109 255 −102 256 390 257 −111258 −413 259 −230 260 384 261 45 262 285 263 386 264 −232 265 −19 266 41267 −22 268 72 269 −131 270 −376 271 226 272 219 273 126 274 395 275 180276 −76 277 315 278 −335 279 −418 280 −3 281 209 282 −360 283 −252 284387 285 262 286 44 287 38 288 67 289 −90 290 −379 291 222 292 204 293−63 294 117 295 310 296 −411 297 −113 298 183 299 188 300 165 301 −354302 25 303 −36 304 −69 305 11 306 −85 307 399 308 −79 309 −410 310 295311 116 312 320 313 −193 314 −334 315 277 316 −77 317 397 318 124 319−192 320 312 321 115 322 −185 323 −213 324 246 325 −364 326 −332 327−195 328 243 329 51 330 150 331 365 332 −326 333 194 334 −314 335 −278336 417 337 239 338 −350 339 −99 340 343 341 −342 342 −341 343 340 344−100 345 107 346 371 347 −162 348 −176 349 −238 350 −338 351 98 352 −174353 −164 354 −301 355 −26 356 403 357 47 358 382 359 −208 360 −282 361251 362 197 363 −245 364 −325 365 331 366 149 367 16 368 −57 369 216 370−161 371 346 372 106 373 −9 374 83 375 132 376 −270 377 −227 378 91 379−290 380 −223 381 −207 382 358 383 46 384 260 385 −231 386 263 387 284388 −253 389 −110 390 256 391 −103 392 −122 393 190 394 181 395 274 396125 397 317 398 −78 399 307 400 −86 401 −136 402 48 403 356 404 −27 40529 406 −31 407 235 408 146 409 80 410 −309 411 −296 412 112 413 −258 414229 415 −93 416 240 417 336 418 −279 419 2

Table 3 lists du_(HT)(u) values when Nzc=139, where u=1, . . . , 69.When u=70, . . . , 138, du_(HT)(u) values can be obtained using aformula du_(HT)(Nzu−u)=−du_(HT) (u), u=1, . . . , 69.

TABLE 3 Values of du_(HT) when N_(ZC) = 139 u du_(HT) 1 −1 2 69 3 46 4−35 5 −28 6 23 7 −20 8 52 9 −31 10 −14 11 −38 12 −58 13 32 14 −10 15 3716 26 17 49 18 54 19 −22 20 −7 21 −53 22 −19 23 6 24 −29 25 50 26 16 2736 28 −5 29 −24 30 −51 31 −9 32 13 33 −59 34 −45 35 −4 36 27 37 15 38−11 39 57 40 66 41 61 42 43 43 42 44 60 45 −34 46 3 47 68 48 55 49 17 5025 51 −30 52 8 53 −21 54 18 55 48 56 67 57 39 58 −12 59 −33 60 44 61 4162 65 63 −64 64 −63 65 62 66 40 67 56 68 47 69 2

Then, determine start positions of the N detection windows of the i^(th)ZC sequence according to the du_(HT) value of the i^(th) ZC sequence.

The number N of detection windows may be preset inside a base stationaccording to a frequency deviation range, or may be dynamicallyconfigured to the base station on an operation and maintenance console.

For example, as an embodiment, when the frequency deviation range is

$\left\lbrack {{- \frac{5*\Delta \; f_{RA}}{2}},\frac{5*\Delta \; f_{RA}}{2}} \right\rbrack,$

the number of detection windows of the ZC sequence may be configured tofive, and, however, the number of detection windows of the ZC sequencemay also be configured to more than five. When the frequency deviationrange is

$\left\lbrack {{- \frac{W*\Delta \; f_{RA}}{2}},\frac{W*\Delta \; f_{RA}}{2}} \right\rbrack$

and W>5, the number N of detection windows of the ZC sequence may beconfigured to W, and the number N of detection windows of the ZCsequence may also be configured to more than W.

Finally, set the N detection windows of the i^(th) ZC sequence accordingto start positions of the N detection windows of the i^(th) ZC sequenceand a preset size of a detection window.

The size of a detection window may be preset according to the cellradius, and the window size is no less than an RTD corresponding to thecell radius. For example, based on the RTD corresponding to the cellradius, the detection window may be expanded according to a multipathdelay.

102. Send the cell type, a second Ncs, and the ZC sequence group to auser equipment UE, so that the UE selects a random access sequence fromthe ZC sequence group.

The second Ncs refers to an index value that can ensure that the UE usesthe ZC root sequence in the ZC sequence group as a random accesssequence. For example, two configuration manners in the following may beused.

Manner 1: When the cell type is configured to unrestricted cell (orlow-speed cell), the second Ncs index is 0.

Manner 2: When the cell type is configured to restricted cell (orhigh-speed cell), the second Ncs index is 14.

In manner 2, the second Ncs index is not limited to 14, and may be anyother index that enables the UE to use a ZC sequence which does notshift cyclically as the random access sequence, so as to reduce anoverlap probability of the N detection windows of the ZC sequence. Thesecond Ncs may be set inside the base station, or determined accordingto the configured cell type inside the base station, or obtained byquerying a table, and is sent to the UE in a system message.

It should be noted that the first Ncs in step 101 is set according tothe cell coverage range, and reflects the cell coverage radius. Thesecond Ncs in step 102 is only used to be sent to the UE, so that the UEuses the ZC root sequence in the ZC sequence group as the random accesssequence rather than uses a ZC sequence that shifts cyclically as therandom access sequence, which can reduce the overlap probability of theN detection windows. If the index value of the first Ncs in step 101meets a condition of enabling the UE to use the ZC sequence which doesnot shift cyclically as the random access sequence, the first Ncs andthe second Ncs may be the same.

Partial ZC sequences in the ZC sequence group are used for contentionaccess, and partial ZC sequences are used for contention-free access.For contention access, the UE randomly selects one ZC sequence from ZCsequences used for contention access in the ZC sequence group as therandom access sequence. For contention-free access, the base stationindicates to the UE which ZC sequence in the ZC sequence group is to beused as the random access sequence.

103. Receive a random access signal sent by the UE, and obtain therandom access sequence from the random access signal.

104. Perform correlation processing (correlation) on the random accesssequence with each ZC sequence in the ZC sequence group, detect a validpeak value in the N detection windows of each ZC sequence, and determinean estimated value of a round trip delay RTD according to the valid peakvalue.

The valid peak value is obtained by determining a maximum peak value ineach detection window and a position of the maximum peak value in eachdetection window, and is specifically described as follows:

When only one maximum peak value is greater than a detection threshold,the peak value greater than the detection threshold is selected as thevalid peak value. The valid peak value may also be called a primary peakvalue.

When two or more than two maximum peak values are greater than thedetection threshold, whether absolute positions of the two maximum peakvalues overlap is determined. If the absolute positions do not overlap,the two maximum peak values are selected as valid peak values, where agreater valid peak value in the two valid peak values is called aprimary peak value and a smaller valid peak value in the two valid peakvalues is called a secondary peak value. If the absolute positionsoverlap, the two maximum peak values are the same peak value and used asthe primary peak value, and a maximum peak value greater than thedetection threshold detected in a detection window corresponding to aspacing of the frequency deviation of the detection window in which theprimary peak value is located plus 1 or the frequency deviation minus 1RACH subcarriers is a secondary peak value.

The detection threshold may be set according to a false-alarmperformance requirement under discontinuous transmission.

The estimated value of the RTD is a deviation of the valid peak valuerelative to a start position of a detection window in which the validpeak value is located. If the start position of the detection window inwhich the valid peak value is located is shifted based on the startposition determined according to the du_(HT) value of the ZC sequence,the estimated value of the RTD may be obtained according to a deviationvalue of the valid peak value relative to the start position of thedetection window in which the valid peak value is located, a shiftdirection and shift sampling points, which is specifically described asfollows:

Assuming that the start position of the detection window in which thevalid peak value is located shifts left by preset sampling points, theestimated value of the RTD is a deviation value of the valid peak valuerelative to the start position of the detection window in which thevalid peak value is located minus the number of the preset samplingpoints. Assuming that the start position of the detection window inwhich the valid peak value is located shifts right by the presetsampling points, the estimated value of the RTD is a deviation value ofthe valid peak value relative to the start position of the detectionwindow in which the valid peak value is located plus the number of thepreset sampling points.

By using the method for processing very-high-speed random accessprovided by the foregoing embodiment, a problem that an RTD of a randomaccess signal cannot be correctly detected in a very-high-speed scenariois solved, it is ensured that a user equipment moving at a very highspeed can correctly adjust a TA value according to a detected RTD, andtherefore message sending timing is correctly adjusted, so that the userequipment in a very-high-speed scenario can normally access a network,thereby improving access performance of the network.

As shown in FIG. 2, a method for processing very-high-speed randomaccess according to an embodiment of the present invention, where Ndetection windows are set for each ZC sequence in a ZC sequence groupwhen a frequency deviation range of very-high-speed random access is

$\left\lbrack {{- \frac{5*\Delta \; f_{RA}}{2}},\frac{5*\Delta \; f_{RA}}{2}} \right\rbrack,$

where N=5, is specifically described as follows:

201. Select a ZC sequence group according to a cell type and a firstNcs.

For relevant descriptions of the cell type and the first Ncs as well asthe ZC sequence group, refer to step 101.

The selecting a ZC sequence group according to a cell type and a firstNcs is specifically described as follows:

B1. Select the ZC sequence group according to the cell type and thefirst Ncs.

B2. Determine whether a du_(HT) value of each ZC sequence in the ZCsequence group meets a condition

${{du}_{HT}} \in {\left\lbrack {{Ncs},\frac{{Nzc} - {Ncs}}{4}} \right\rbrack\bigcup{\quad{{\left\lbrack {\frac{{Nzc} + {Ncs}}{4},\frac{{Nzc} - {Ncs}}{3}} \right\rbrack\bigcup\left\lbrack {\frac{{Nzc} + {Ncs}}{3},\frac{{Nzc} - {Ncs}}{2}} \right\rbrack},}}}$

where Nzc is a length of each ZC sequence, and Ncs refers to the firstNcs;

if the du_(HT) value of at least one ZC sequence in the ZC sequencegroup does not meet the condition, return to step B1; and

if du_(HT) values of the ZC sequences in the ZC sequence group all meetthe condition, send the ZC sequence group to a user equipment;

where, for an obtaining manner of the du_(HT) value, reference may bemade to relevant descriptions in step 101.

It should be noted that, when the du_(HT) value of each ZC sequence inthe selected ZC sequence group meets the condition

${{du}_{HT}} \in {\left\lbrack {{Ncs},\frac{{Nzc} - {Ncs}}{4}} \right\rbrack\bigcup{\quad{{\left\lbrack {\frac{{Nzc} + {Ncs}}{4},\frac{{Nzc} - {Ncs}}{3}} \right\rbrack\bigcup\left\lbrack {\frac{{Nzc} + {Ncs}}{3},\frac{{Nzc} - {Ncs}}{2}} \right\rbrack},}}}$

the five detection windows set according to the du_(HT) value of each ZCsequence do not overlap, which improves correctness of RTD estimation.

For example, assuming that the cell type is restricted cell, the firstNcs set according to a cell radius is 15, the selected ZC sequence groupincludes 64 ZC sequences, and a length of a ZC sequence is 839, a methodfor selecting the ZC sequence group according to the cell type and thefirst Ncs is described with an example as follows:

First, select logical root sequence numbers of the 64 ZC sequencesaccording to the cell type and the first Ncs.

Table 4 is a mapping table between Ncs values and logical root sequencenumbers of a restricted cell. The first column includes two Ncs valuesof 15, where a first logical root sequence number corresponding to thefirst Ncs of 15 is 24, and a second logical root sequence numbercorresponding to the second Ncs of 15 is 819. Therefore, availablelogical root sequence numbers are [24, 819] when the first Ncs is 15.

TABLE 4 Mapping table between Ncs values and logical root sequencenumbers of a restricted cell N_(CS) value (restricted cell) Logical rootsequence number —  0-23 15 24-29 18 30-35 22 36-41 26 42-51 32 52-63 3864-75 46 76-89 55  90-115 68 116-135 82 136-167 100 168-203 128 204-263158 264-327 202 328-383 237 384-455 237 456-513 202 514-561 158 562-629128 630-659 100 660-707 82 708-729 68 730-751 55 752-765 46 766-777 38778-789 32 790-795 26 796-803 22 804-809 18 810-815 15 816-819 — 820-837

Then, obtain the physical root sequence numbers of the 64 ZC sequencesaccording to a mapping table between the logical root sequence numbersand the physical root sequence numbers.

Table 5 provides the mapping between partial logical root sequencenumbers and partial physical root sequence numbers.

TABLE 5 Mapping table between logical root sequence numbers and physicalroot sequence numbers Logical root sequence number Physical rootsequence number (Logical root sequence number) (Physical root sequencenumber u)  0-23 129, 710, 140, 699, 120, 719, 210, 629, 168, 671, 84,755, 105, 734, 93, 746, 70, 769, 60, 7792, 837, 1, 838 24-29 56, 783,112, 727, 148, 691 30-35 80, 759, 42, 797, 40, 799 36-41 35, 804, 73,766, 146, 693 42-51 31, 808, 28, 811, 30, 809, 27, 812, 29, 810 52-6324, 815, 48, 791, 68, 771, 74, 765, 178, 661, 136, 703 64-75 86, 753,78, 761, 43, 796, 39, 800, 20, 819, 21, 818 76-89 95, 744, 202, 637,190, 649, 181, 658, 137, 702, 125, 714, 151, 688  90-115 217, 622, 128,711, 142, 697, 122, 717, 203, 636, 118, 721, 110, 729, 89, 750, 103,736, 61, 778, 55, 784, 15, 824, 14, 825 116-135 12, 827, 23, 816, 34,805, 37, 802, 46, 793, 207, 632, 179, 660, 145, 694, 130, 709, 223, 616136-167 228, 611, 227, 612, 132, 707, 133, 706, 143, 696, 135, 704, 161,678, 201, 638, 173, 666, 106, 733, 83, 756, 91, 748, 66, 773, 53, 786,10, 829, 9, 830 168-203 7, 832, 8, 831, 16, 823, 47, 792, 64, 775, 57,782, 104, 735, 101, 738, 108, 731, 208, 631, 184, 655, 197, 642, 191,648, 121, 718, 141, 698, 149, 690, 216, 623, 218, 621 204-263 152, 687,144, 695, 134, 705, 138, 701, 199, 640, 162, 677, 176, 663, 119, 720,158, 681, 164, 675, 174, 665, 171, 668, 170, 669, 87, 752, 169, 670, 88,751, 107, 732, 81, 758, 82, 757, 100, 739, 98, 741, 71, 768, 59, 780,65, 774, 50, 789, 49, 790, 26, 813, 17, 822, 13, 826, 6, 833 264-327 5,834, 33, 806, 51, 788, 75, 764, 99, 740, 96, 743, 97, 742, 166, 673,172, 667, 175, 664, 187, 652, 163, 676, 185, 654, 200, 639, 114, 725,189, 650, 115, 724, 194, 645, 195, 644, 192, 647, 182, 657, 157, 682,156, 683, 211, 628, 154, 685, 123, 716, 139, 700, 212, 627, 153, 686,213, 626, 215, 624, 150, 689 328-383 225, 614, 224, 615, 221, 618, 220,619, 127, 712, 147, 692, 124, 715, 193, 646, 205, 634, 206, 633, 116,723, 160, 679, 186, 653, 167, 672, 79, 760, 85, 754, 77, 762, 92, 747,58, 781, 62, 777, 69, 770, 54, 785, 36, 803, 32, 807, 25, 814, 18, 821,11, 828, 4, 835 384-455 3, 836, 19, 820, 22, 817, 41, 798, 38, 801, 44,795, 52, 787, 45, 794, 63, 776, 67, 772, 72 767, 76, 763, 94, 745, 102,737, 90, 749, 109, 730, 165, 674, 111, 728, 209, 630, 204, 635, 117,722, 188, 651, 159, 680, 198, 641, 113, 726, 183, 656, 180, 659, 177,662, 196, 643, 155, 684, 214, 625, 126, 713, 131, 708, 219, 620, 222,617, 226, 613 456-513 230, 609, 232, 607, 262, 577, 252, 587, 418, 421,416, 423, 413, 426, 411, 428, 376, 463, 395, 444, 283, 556, 285, 554,379, 460, 390, 449, 363, 476, 384, 455, 388, 451, 386, 453, 361, 478,387, 452, 360, 479, 310, 529, 354, 485, 328, 511, 315, 524, 337, 502,349, 490, 335, 504, 324, 515 . . . . . .

If the selected logical root sequence number is 384, the physical rootsequence numbers of the 64 ZC sequences may be obtained according to themapping between the logical root sequence numbers and the physical rootsequence numbers in Table 5 as follows: 3, 836, 19, 820, 22, 817, 41,798, 38, 801, 44, 795, 52, 787, 45, 794, 63, 776, 67, 772, 72, 767, 76,763, 94, 745, 102, 737, 90, 749, 109, 730, 165, 674, 111, 728, 209, 630,204, 635, 117, 722, 188, 651, 159, 680, 198, 641, 113, 726, 183, 656,180, 659, 177, 662, 196, 643, 155, 684, 214, 625, 126, 713.

Then, obtain du_(HT) values of the 64 ZC sequences.

According to relevant descriptions and obtaining method of du_(HT) instep 101, it may be obtained that: when the physical root sequencenumber u=3, du_(HT)=−280; when the physical root sequence number u=836,du_(HT)=280; and when the physical root sequence number u=19,du_(HT)=265, . . . .

Finally, determine whether the du_(HT) values of the selected 64 ZCsequences all meet a condition

${{du}_{HT}} \in {\left\lbrack {{Ncs},\frac{{Nzc} - {Ncs}}{4}} \right\rbrack\bigcup{\quad{\left\lbrack {\frac{{Nzc} + {Ncs}}{4},\frac{{Nzc} - {Ncs}}{3}} \right\rbrack\bigcup{\left\lbrack {\frac{{Nzc} + {Ncs}}{3},\frac{{Nzc} - {Ncs}}{2}} \right\rbrack.}}}}$

If the condition is not met, reselect the ZC sequence group.

|du_(HT)|∈[15,206]∪[213,274]∪[284,412] is worked out by calculatingaccording to the first Ncs and Nzc. In the selected 64 ZC sequences,when the physical root sequence numbers are 3 and 836, the du_(HT)values do not meet the du_(HT) value condition. Therefore, reselect 64ZC sequences according to the selecting step of the ZC sequence group.

Assuming that the physical root sequence numbers of the reselected 64 ZCsequences are 56, 783, 112, 727, 148, 691, 80, 759, 42, 797, 40, 799,35, 804, 73, 766, 146, 693, 31, 808, 28, 811, 30, 809, 29, 810, 27, 812,24, 815, 48, 791, 68, 771, 74, 765, 178, 661, 136, 703, 86, 753, 78,761, 43, 796, 39, 800, 20, 819, 21, 818, 95, 744, 202, 637, 190, 649,181, 658, 137, 702, 125, 714, obtain du_(HT) values and determine thatthe du_(HT) values of the reselected 64 ZC sequences meet the du_(HT)condition.

202. Set N detection windows for each ZC sequence in the ZC sequencegroup, where N=5.

When the ZC sequence group includes M ZC sequences, the setting Ndetection windows for each ZC sequence in the ZC sequence group, whereN=5, is specifically described as follows:

C1. Obtain a du_(HT) value of an i^(th) ZC sequence in the ZC sequencegroup.

The du_(HT) value of the i^(th) ZC sequence refers to a shift of amirror image peak in a power delay profile PDP of the i^(th) ZC sequencerelative to the RTD when a frequency deviation is

${\pm \frac{1}{T_{SEQ}}},$

where T_(SEQ) is a time duration occupied by the i^(th) ZC sequence anda value of i is any integer in [1, M].

C2. Set five detection windows of the i^(th) ZC sequence according tothe du_(HT) value of the i^(th) ZC sequence.

First, obtain start positions of the five detection windows of thei^(th) ZC sequence according to the du_(HT) value of the i^(th) ZCsequence.

The five detection windows of the i^(th) ZC sequence are a detectionwindow {circle around (1)}, a detection window {circle around (2)}, adetection window {circle around (3)}, a detection window {circle around(4)} and a detection window {circle around (5)}, respectively. The fivedetection windows {circle around (1)}, {circle around (2)}, {circlearound (3)}, {circle around (4)} and {circle around (5)} respectivelycorrespond to frequency deviations 0, −Δf_(RA), +Δf_(RA), −2Δf_(RA) and+2Δf_(A). The details are as follows:

a start position of the detection window {circle around (1)} is 0;

a start position of the detection window {circle around (2)} ismod(du_(HT), Nzc);

a start position of the detection window {circle around (3)} ismod(−du_(HT), Nzc);

a start position of the detection window {circle around (4)} ismod(2*du_(HT), Nzc); and

a start position of the detection window {circle around (5)} ismod(−2*du_(HT), Nzc);

where mod(du_(HT), Nzc) means du_(HT) mod Nzc, Nzc is a length of thei^(th) ZC sequence, and for an obtaining manner of the du_(HT) value,reference may be made to step 101.

Then, set the five detection windows of the i^(th) ZC sequence accordingto the start positions of the five detection windows and a preset sizeof a detection window.

The size of the detection window is consistent with relevantdescriptions in step 101. The start position of the detection window maybe shifted according to preset sampling points, so as to adapt toearlier or later transmission of a random access signal by a UE.

203. Send the cell type, a second Ncs, and the ZC sequence group to aUE, so that the UE selects a random access sequence from the ZC sequencegroup.

For relevant descriptions of the second Ncs, refer to step 102.

204. Receive a random access signal sent by the UE, and obtain therandom access sequence from the random access signal.

205. Perform correlation processing on the random access sequence witheach ZC sequence in the ZC sequence group, detect a valid peak value inthe five detection windows of each ZC sequence, and determine anestimated value of an RTD according to the valid peak value.

The valid peak value and the estimated value of the RTD are consistentwith relevant descriptions in step 104.

The determining the RTD according to the valid peak value may beobtained by using two methods as follows:

Method (1): Directly obtain the estimated value of the RTD according toa deviation of a primary peak value relative to a start position of aprimary peak value detection window.

Method (2): Select and merge data of at least two detection windowsaccording to a preset principle to obtain a new valid peak value, andestimate the RTD.

In the method (2), according to the preset principle, detection windowsat two sides of the primary peak value may be merged, or a detectionwindow in which the primary peak value is located and a detection windowin which a secondary peak value is located may be merged, or all thedetection windows may be merged. Since the detection windows are merged,a detection threshold of the valid peak value is increased accordingly.Therefore, a new valid peak value may be obtained, and the RTD may beestimated according to the obtained new effective value.

206. Estimate a frequency deviation according to a detection window inwhich the valid peak value is located.

An estimated value of the frequency deviation is used for rectifying adeviation of an uplink signal of the UE and demodulating a Message 3message sent by the UE. The Message 3 carries an identifier of the UE.

FIG. 3 is a schematic diagram illustrating changing of a valid peakvalue with frequency deviations in detection windows. The estimating afrequency deviation according to a detection window in which the validpeak value is located specifically includes three cases as follows:

Case 1: When two valid peak values exist, if a primary peak value islocated in a detection window {circle around (1)} and a secondary peakvalue is located in a detection window {circle around (3)}, a frequencydeviation of an uplink signal of a UE may be estimated to be a valuewithin a range of 0 to ½Δf_(RA) according to the schematic diagram ofthe peak values in each window changing with the frequency deviation asshown in FIG. 3. If a maximum peak value is in the detection window{circle around (3)} and a second maximum peak value is in a detectionwindow {circle around (5)}, the frequency deviation of the uplink signalof the UE is estimated to be a value within a range of Δf_(RA) to3/2Δf_(RA); and so on.

Case 2: If two valid peak values exist and are close, where one islocated in the detection window {circle around (1)} and the other islocated in the detection window {circle around (3)}, the frequencydeviation of the uplink signal of the UE is estimated to be about½Δf_(RA); if two valid peak values exist and are close, where one islocated in the detection window {circle around (3)} and the other islocated in the detection window {circle around (5)}, the frequencydeviation of the uplink signal of the UE is estimated to be about3/2Δf_(RA); and so on.

Case 3: If one valid peak value exists and is located in the detectionwindow {circle around (1)}, the frequency deviation of the uplink signalof the UE is estimated to be 0; if one valid peak value exists and islocated in the detection window {circle around (2)}, the frequencydeviation of the uplink signal of the UE is estimated to be −Δf_(RA); ifone valid peak value exists and is located in the detection window{circle around (4)}, the frequency deviation of the uplink signal of theUE is estimated to be −2Δf_(RA); and so on.

It should be noted that step 205 is optional. To be specific, thefrequency deviation is not estimated. Instead, a Message 3 isdemodulated by grades according to a frequency deviation range. Forexample, when the frequency deviation range is [−3 KHz, 3 KHz],demodulation may be performed by six grades, where 1 KHz is a grade.

In the method for processing very-high-speed random access provided bythe foregoing embodiment, a ZC sequence group is selected according to acell type and a first Ncs, it is ensured that du_(HT) values of ZCsequences in the ZC sequence group meet a condition

${{du}_{HT}} \in {\left\lbrack {{Ncs},\frac{{Nzc} - {Ncs}}{4}} \right\rbrack\bigcup{\quad{{\left\lbrack {\frac{{Nzc} + {Ncs}}{4},\frac{{Nzc} - {Ncs}}{3}} \right\rbrack\bigcup\left\lbrack {\frac{{Nzc} + {Ncs}}{3},\frac{{Nzc} - {Ncs}}{2}} \right\rbrack},}}}$

N non-overlap detection windows are set for each ZC sequence in the ZCsequence group according to the du_(HT) value of each ZC sequence in theZC sequence group, where N=5, the valid peak values in the non-overlapdetection windows are detected, and a round trip delay is determined. Inthis way, not only a problem of access of a UE to a network in avery-high-speed scenario where the frequency deviation range is

$\left\lbrack {{- \frac{5*\Delta \; f_{RA}}{2}},\frac{5*\Delta \; f_{RA}}{2}} \right\rbrack$

is solved, but also correctness of an estimated value of the RTD isimproved.

As shown in FIG. 4, a method for processing very-high-speed randomaccess according to an embodiment of the present invention, where Ndetection windows are set for each ZC sequence in a ZC sequence groupwhen a frequency deviation range of the very-high-speed random access is

$\left\lbrack {{- \frac{5*\Delta \; f_{RA}}{2}},\frac{5*\Delta \; f_{RA}}{2}} \right\rbrack,$

where N=5, is specifically described as follows:

401. Select a ZC sequence group according to a cell type and a firstNcs.

The cell type is a restricted cell, and the first Ncs represents acoverage range of the restricted cell.

Selection of the ZC sequence group may be obtained according to aselecting principle for root sequences of the restricted cell in theprior art, and therefore is not described herein any further.

402. Set N detection windows for each ZC sequence in the ZC sequencegroup, where N=5.

For relevant descriptions of the setting N detection windows for each ZCsequence in the ZC sequence group, reference may be made to step 202.

403. Send the cell type, a second Ncs, and the ZC sequence group to aUE, so that the UE selects a random access sequence from the ZC sequencegroup.

For relevant descriptions of the second Ncs, refer to step 102.

404. Receive a random access signal sent by the UE, and obtain therandom access sequence from the random access signal.

405. Perform correlation processing on the random access sequence witheach ZC sequence in the ZC sequence group, detect a primary peak valuein the five detection windows of each ZC sequence, and determine asearch window for a secondary peak value according to the primary peakvalue.

Search one maximum peak value in each of the five detection windows ofeach ZC sequence, and determine whether absolute positions of twomaximum peak values in the five maximum peak values overlap. If theabsolute positions do not overlap, select a greater maximum peak valueof the two maximum peak values as the primary peak value. If theabsolute positions overlap, select windows in which the two maximum peakvalues are located as windows in which the primary peak value islocated. For example, when the primary peak value appears in an overlapbetween two detection windows, the primary peak value is detectedseparately in the two detection windows, that is, the same peak value isdetected twice. Therefore, whether the peak values are the same peakvalue may be determined by determining whether the absolution positionsof the two maximum peak values overlap.

TABLE 6 Search window for secondary peak value Window where the primarySearch window for peak value is located secondary peak value {circlearound (1)} {circle around (2)}{circle around (3)} {circle around (2)}{circle around (1)}{circle around (4)} {circle around (3)} {circlearound (1)}{circle around (5)} {circle around (4)} {circle around (2)}{circle around (5)} {circle around (3)} {circle around (2)}{circlearound (5)} {circle around (1)}{circle around (3)} {circle around(3)}{circle around (4)} {circle around (1)}{circle around (2)} {circlearound (4)}{circle around (5)} {circle around (2)}{circle around (3)}

For example, assuming that the primary peak value appears in an overlapbetween a detection window {circle around (4)} and a detection window{circle around (5)}, it can be known by referring to Table 6 that searchwindows for the secondary peak value are a window {circle around (2)}and a window {circle around (3)}.

406. Detect a secondary peak value in the search window for thesecondary peak value, and determine, according to a combination of thedetection window in which the primary peak value is located and adetection window in which the secondary peak value is located, afrequency deviation estimation window combination and an RTD estimationwindow.

Detect a secondary peak value in the search window for the secondarypeak value. To be specific, find one maximum peak value in the searchwindow for each secondary peak value, compare the maximum peak values,and select a greatest one which is greater than a detection threshold asthe secondary peak value.

Determine the frequency deviation estimation window combination and theRTD estimation window by querying Table 7 according to the window inwhich the secondary peak value is located and the window in which theprimary peak value is located.

For example, assuming that the primary peak value appears in an overlapbetween the detection window {circle around (4)} and the detectionwindow {circle around (5)}, it can be known by referring to Table 7 thatthe secondary peak value is searched in the window {circle around (2)}and the window {circle around (3)}. When the secondary peak value isfound in the detection window {circle around (2)}, the combination ofdetection windows after two peak value searches is {circle around (2)},{circle around (4)} and {circle around (5)}. It can be known byreferring to Table 7 that the detection window {circle around (4)} isselected to estimate the RTD, and the detection windows {circle around(2)} and {circle around (4)} are selected to estimate the frequencydeviation. When the secondary peak value is found in the detectionwindow {circle around (3)}, a combination of detection windows after twopeak value searches is {circle around (3)}, {circle around (4)} and{circle around (5)}. It can be known by referring to Table 7 that thedetection window {circle around (5)} is selected to estimate the RTD,and the detection windows {circle around (3)} and {circle around (5)}are selected to estimate the frequency deviation.

TABLE 7 Frequency deviation estimation window combination and RTDestimation window Window combination Frequency deviation after two peakestimation window value searches combination RTD estimation window{circle around (1)} Invariant Single window itself {circle around (2)}{circle around (3)} {circle around (4)} {circle around (5)} {circlearound (1)}{circle around (2)} Window in which the {circle around(1)}{circle around (3)} primary peak value is {circle around (2)}{circlearound (4)} located {circle around (3)}{circle around (5)} {circlearound (2)}{circle around (5)} fail — {circle around (3)}{circle around(4)} {circle around (2)}{circle around (3)}{circle around (4)} {circlearound (2)}{circle around (3)}{circle around (5)} {circle around(2)}{circle around (3)}{circle around (4)}{circle around (5)} {circlearound (4)}{circle around (5)} {circle around (1)}{circle around(2)}{circle around (5)} {circle around (1)}{circle around (2)} {circlearound (2)} {circle around (1)}{circle around (3)}{circle around (4)}{circle around (1)}{circle around (3)} {circle around (3)} {circlearound (2)}{circle around (4)}{circle around (5)} {circle around(2)}{circle around (4)} {circle around (4)} {circle around (3)}{circlearound (4)}{circle around (5)} {circle around (3)}{circle around (5)}{circle around (5)}

It should be noted that, if the frequency deviation estimation windowcombination shows fail, no user is detected in the detection windows ofthe ZC sequence. Otherwise, the RTD is estimated according to adesignated RTD estimation window.

407. Determine the estimated value of the RTD according to a position ofthe valid peak value in the RTD estimation window.

The estimated value of the RTD is a deviation of the valid peak value inthe RTD estimation window relative to a start position of the RTDestimation window. If the start position of the RTD estimation window isobtained by shifting preset sampling points, the estimated value of theRTD is a deviation value of the valid peak value in the RTD estimationwindow relative to the start position of the RTD estimation window plusor minus the number of the preset sampling points. The details are asfollows.

Assuming that the start position of the RTD estimation window shiftsleft by the preset sampling points, the estimated value of the RTD isthe deviation value of the start position of the RTD estimation windowminus the number of the preset sampling points. Assuming that the startposition of the RTD estimation window shifts right by the presetsampling points, the estimated value of the RTD is the deviation valueof the start position of the RTD estimation window plus the number ofthe preset sampling points.

408. Determine an estimated value of the frequency deviation accordingto the frequency deviation estimation window combination.

For how to determine the estimated value of the frequency deviationaccording to the frequency deviation estimation window combination,reference may be made to relevant descriptions in step 206.

The estimated value of the frequency deviation is used for rectifying adeviation of an uplink signal of the UE, thereby demodulating a Message3.

It should be noted that step 408 is optional. To be specific, thefrequency deviation may not be estimated. Instead, a Message 3 isdemodulated by grades according to a frequency deviation range. Forexample, when the frequency deviation range is [−3 KHz, 3 KHz],demodulation may be performed by six grades, where 1 KHz is a grade.

In the method for processing very-high-speed random access provided bythe foregoing embodiment, a principle of selecting the ZC sequence forthe restricted cell in the prior art is used to select a ZC sequencegroup, the five detection windows is set for each ZC sequence in the ZCsequence group, the valid peak value in the five detection windows ofeach ZC sequence is detected, and an RTD estimation window is determinedaccording to a combination of the detection window in which the primarypeak value is located and the detection window in which the secondarypeak value is located, so that the estimated value of the RTD isdetermined. In this way, a problem of detecting the RTD when the validpeak value appears in the overlap between detection windows is solved,and processing of the random access signal in a very-high-speed movementscenario when the frequency deviation range is

$\left\lbrack {{- \frac{5*\Delta \; f_{RA}}{2}},\frac{5*\Delta \; f_{RA}}{2}} \right\rbrack$

is implemented, thereby improving access performance of a network.

As shown in FIG. 5, a method for processing very-high-speed randomaccess according to an embodiment of the present invention, where N(N≥W) detection windows are set for each ZC sequence in a ZC sequencegroup when a frequency deviation range of the very-high-speed randomaccess is

$\left\lbrack {{- \frac{W*\Delta \; f_{RA}}{2}},\frac{W*\Delta \; f_{RA}}{2}} \right\rbrack,$

where W≥5, is specifically described as follows:

501. Select a ZC sequence group according to a cell type and a firstNcs.

Selection of the ZC sequence group is obtained according to aconfiguration principle for root sequences of a restricted cell, whichbelongs to the prior art, and therefore is not described herein anyfurther.

For relevant descriptions of the cell type and the first Ncs, refer tostep 101.

502. Set N detection windows for each ZC sequence in the ZC sequencegroup.

When the ZC sequence group includes M ZC sequences, the setting Ndetection windows for each ZC sequence in the ZC sequence group isspecifically described as follows:

D1. Obtain a du_(HT) value of an i^(th) ZC sequence in the ZC sequencegroup.

For relevant descriptions of the du_(HT) value and an obtaining method,reference may be made to step 101, where a value of i is any integer in[1, M].

D2. Determine start positions of the N detection windows of the i^(th)ZC sequence according to the du_(HT) value of the i^(th) ZC sequence.

The N detection windows {circle around (1)}, {circle around (2)},{circle around (3)}, {circle around (4)}, {circle around (5)}, {circlearound (6)}, {circle around (7)} . . . of the i^(th) ZC sequencerespectively correspond to frequency deviations0/−Δf_(RA)/+Δf_(RA)/−2Δf_(RA)/+2Δf_(RA)/−3Δf_(RA)/+3Δf_(RA)/, . . . .The start positions are as follows:

a start position of the detection window {circle around (1)} is 0;

a start position of the detection window {circle around (2)} ismod(du_(HT), Nzc);

a start position of the detection window {circle around (3)} ismod(−du_(HT), Nzc);

a start position of the detection window {circle around (4)} ismod(2*du_(HT), Nzc);

a start position of the detection window {circle around (5)} ismod(−2*du_(HT), Nzc);

a start position of the detection window {circle around (6)} ismod(3*du_(HT), Nzc);

a start position of the detection window {circle around (7)} ismod(−3*du_(HT), Nzc); and

others can be so deduced;

where mod(du_(HT), Nzc) means du_(HT) mod Nzc, and Nzc is a length ofthe i^(th) ZC sequence.

D3. Set the N detection windows of the i^(th) ZC sequence according tothe start positions of the N detection windows of the i^(th) ZC sequenceand a preset size of a detection window.

The size of the detection window may be configured according to a cellradius, and is no less than an RTD corresponding to the cell radius.

503. Send the cell type, a second Ncs, and the ZC sequence group to aUE, so that the UE selects a random access sequence from the ZC sequencegroup.

For relevant descriptions of the second Ncs, refer to step 102.

504. Receive a random access signal sent by the UE, and obtain therandom access sequence from the random access signal.

505. Perform correlation processing on the random access sequence witheach ZC sequence in the ZC sequence group, detect a valid peak value inthe N detection windows of each ZC sequence, and determine an estimatedvalue of the RTD according to the valid peak value.

For relevant descriptions of the valid peak value, reference may be madeto step 104.

The determining an estimated value of the RTD according to the validpeak value may include step E1 and step E2, which are specificallydescribed as follows:

E1. Determine an RTD estimation window according to a detection windowin which the valid peak value is located.

If the detection window of the ZC sequence in which the valid peak valueis located does not overlap with other detection windows of the ZCsequence, randomly select one from the detection windows in which thevalid peak value is located as the RTD estimation window; or,

if the detection window of the ZC sequence in which the valid peak valueis located overlaps with other detection windows of the ZC sequence butat least one valid peak value appears in a non-overlap, determine adetection window in which the at least one valid peak value is locatedas the RTD estimation window; or,

if the detection window of the ZC sequence in which the valid peak valueis located overlaps with other detection windows of the ZC sequence, andthe valid peak value appears in the overlap, perform frequency deviationprocessing on the random access signal according to frequency deviationsof two detection windows in which a primary peak value of the valid peakvalues is located to obtain a new valid peak value, and determine thefrequency deviation and the RTD estimation window according to the newvalid peak value.

Other detection windows of the ZC sequence refer to detection windows inthe N detection windows of the ZC sequence except the detection windowin which the valid peak value is located.

For example, assuming that N detection windows are set for each ZCsequence in step 503 and step 504, where N=6. To be specific, each ZCsequence has detection windows {circle around (1)}, {circle around (2)},{circle around (3)}, {circle around (4)}, {circle around (5)} and{circle around (6)}. If valid peak values are respectively detected indetection windows {circle around (3)} and {circle around (5)} of a firstZC sequence, determine whether detection windows {circle around (3)} and{circle around (5)} of the first ZC sequence overlap with otherdetection windows of the first ZC sequence, that is, detection windows{circle around (1)}, {circle around (2)}, {circle around (5)} and{circle around (6)} of the first ZC sequence.

That the detection windows overlap but at least one valid peak valueappears in the non-overlap refers to that although the detection windowsoverlap, at least one valid peak value in the detected valid peak valuesappears in the non-overlap of the detection windows. At this moment, thedetection window in which the valid peak value appearing in thenon-overlap of the detection windows is located is selected to estimatethe RTD. As shown in FIG. 6, it is described as follows by using fivedetection windows as an example.

As shown in FIG. 6(a), when a secondary peak value appears in adetection window {circle around (1)}, the detection window {circlearound (1)} may be used to estimate an RTD.

As shown in FIG. 6(b), a primary peak value appears in an overlapbetween a detection window {circle around (2)} and a detection window{circle around (5)}, and no secondary peak value exists. New valid peakvalues are obtained after a frequency deviation of +1/−2 Δf_(RA) isseparately performed on a received signal, and frequency deviations aredetermined according to the new valid peak values, so as to determine anRTD estimation window.

As shown in FIG. 6(c), a primary peak value appears in an overlapbetween a detection window {circle around (3)} and a detection window{circle around (4)}, and a secondary peak value appears in an overlapbetween the detection window {circle around (2)} and the detectionwindow {circle around (5)}. New valid peak values are obtained after afrequency deviation of −1.5/+1.5 Δf_(RA) is separately performed on thereceived signal, and frequency deviations are determined according tothe new valid peak values, so as to determine the RTD estimation window.

As an embodiment, if the detection window of the ZC sequence in whichthe valid peak value is located overlaps with other detection windows ofthe ZC sequence and the valid peak value appears in the overlap, it isdetermined that no random access signal is detected in the detectionwindow in which the valid peak value is located. Random access initiatedby a UE fails, and access is initiated again.

E2. Determine the estimated value of the RTD according to a position ofthe valid peak value in the RTD estimation window.

For a specific implementation method of step C2, reference may be madeto relevant descriptions in step 407.

It should be noted that the method for processing very-high-speed randomaccess provided by the embodiment is applicable to a case in which afrequency deviation range is

$\left\lbrack {{- \frac{W*\Delta \; f_{RA}}{2}},\frac{W*\Delta \; f_{RA}}{2}} \right\rbrack$

and W≥5. When W≥5, N detection windows are set for the ZC sequences inthe selected ZC sequence group, where N is no less than W.

In the foregoing embodiment, a principle of selecting the ZC sequencefor a restricted cell in the prior art is used to select the ZC sequencegroup, the N detection windows are set for each ZC sequence in the ZCsequence group, the valid peak value in the N detection windows of eachZC sequence is detected, and an RTD estimation window according to adetection window in which the valid peak value is located is determined,so that the round trip delay is determined. In this way, a problem thatit is difficult to detect the RTD correctly in a very-high-speedscenario when a frequency deviation range is

$\left\lbrack {{- \frac{W*\Delta \; f_{RA}}{2}},\frac{W*\Delta \; f_{RA}}{2}} \right\rbrack$

and W≥5 is solved, thereby improving access performance of a network.

As shown in FIG. 7, an apparatus for processing very-high-speed randomaccess according to an embodiment of the present invention may be a basestation, which includes a selecting unit 701, a setting unit 702, asending unit 703, a receiving unit 704, and a detecting unit 705.

The selecting unit 701 is configured to select a ZC sequence groupaccording to a cell type and a first Ncs.

The setting unit 702 is configured to set N detection windows for eachZC sequence in the ZC sequence group, where N≥5.

The sending unit 703 is configured to send the cell type, a second Ncs,and the ZC sequence group selected by the selecting unit 701 to a userequipment UE, so that the UE selects a random access sequence from theZC sequence group.

The receiving unit 704 is configured to receive a random access signalsent by the UE, and obtain the random access sequence from the randomaccess signal.

The detecting unit 705 is configured to perform correlation processingon the random access sequence obtained by the receiving unit 704 witheach ZC sequence in the ZC sequence group, detect a valid peak value inthe N detection windows set by the setting unit 702 for each ZCsequence, and determine an estimated value of a round trip delay RTDaccording to the valid peak value.

Optionally, corresponding to the method embodiment shown in FIG. 1, whenthe ZC sequence group selected by the selecting unit 701 includes M ZCsequences, the setting unit 702 is further configured to:

obtain a du_(HT) value of an i^(th) ZC sequence in the ZC sequencegroup;

determine start positions of the N detection windows of the i^(th) ZCsequence according to the du_(HT) value of the i^(th) ZC sequence; and

set the N detection windows of the i^(th) ZC sequence according to thestart positions of the N detection windows of the i^(th) ZC sequence anda preset size of a detection window.

The du_(HT) value of the i^(th) ZC sequence refers to a shift of amirror image peak in a power delay profile PDP of the i^(th) ZC sequencerelative to the RTD when a frequency deviation is

${\pm \frac{1}{T_{SEQ}}},$

where T_(SEQ) is a time duration occupied by the i^(th) ZC sequence anda value of i is any integer in [1, M]. For an obtaining method of thedu_(HT) value, refer to relevant descriptions in step 101.

The size of a detection window may be configured according to a cellradius, and cannot be less than a maximum value of the RTD.

Optionally, when a frequency deviation range of the very-high-speedaccess is

$\left\lbrack {{- \frac{5*\Delta \; f_{RA}}{2}},\frac{5*\Delta \; f_{RA}}{2}} \right\rbrack$

and the ZC sequence selected by the selecting unit 701 includes M ZCsequences, that is, corresponding to the method embodiment shown in FIG.2, the setting unit 702 is further configured to:

obtain a du_(HT) value of the i^(th) ZC sequence in the ZC sequencegroup; and

set five detection windows of the i^(th) ZC sequence according to thedu_(HT) value of the i^(th) ZC sequence.

The du_(HT) value of the i^(th) ZC sequence refers to a shift of amirror image peak in a power delay profile PDP of the i^(th) ZC sequencerelative to the RTD when a frequency deviation is

${\pm \frac{1}{T_{SEQ}}},$

where T_(SEQ) is a time duration occupied by the i^(th) ZC sequence anda value of i is any integer in [1, M]. For an obtaining method of thedu_(HT) value, refer to relevant descriptions in step 101.

Optionally, when the frequency deviation range of the very-high-speedrandom access is

$\left\lbrack {{- \frac{5*\Delta \; f_{RA}}{2}},\frac{5*\Delta \; f_{RA}}{2}} \right\rbrack$

and N detection windows are set for each ZC sequence in the ZC sequencegroup, where N=5, that is, corresponding to the method embodiment shownin FIG. 2, the setting unit 702 is further configured to:

obtain start positions of the five detection windows of the i^(th) ZCsequence according to the du_(HT) value of the i^(th) ZC sequence, where

a start position of a detection window {circle around (1)} is 0;

a start position of a detection window {circle around (2)} ismod(du_(HT), Nzc);

a start position of a detection window {circle around (3)} ismod(du_(HT), Nzc);

a start position of a detection window {circle around (4)} ismod(2*du_(HT), Nzc);

a start position of a detection window {circle around (5)} ismod(2*du_(HT), Nzc); and set the five detection windows of the i^(th) ZCsequence according to the start positions of the five detection windowsand a preset size of a detection window.

Nzc is a length of the i^(th) ZC sequence. For an obtaining method ofthe du_(HT) value, refer to relevant descriptions in step 101. Forrelevant descriptions of the preset size of the detection window, referto step 104. The five detection windows {circle around (1)}, {circlearound (2)}, {circle around (3)}, {circle around (4)} and {circle around(1)} respectively correspond to frequency deviations 0, −Δf_(RA),+Δf_(RA), −2Δf_(RA) and +2Δf_(RA).

Optionally, when the frequency deviation range of the very-high-speedrandom access is

$\left\lbrack {{- \frac{5*\Delta \; f_{RA}}{2}},\frac{5*\Delta \; f_{RA}}{2}} \right\rbrack$

corresponding to the method embodiment shown in FIG. 2, the setting unit701 is further configured to:

determine whether du_(HT) values of ZC sequences in the selected ZCsequence group meet a condition

${{du}_{HT}} \in {\left\lbrack {{Ncs},\frac{{Nzc} - {Ncs}}{4}} \right\rbrack\bigcup{\quad{{\left\lbrack {\frac{{Nzc} + {Ncs}}{4},\frac{{Nzc} - {Ncs}}{3}} \right\rbrack\bigcup\left\lbrack {\frac{{Nzc} + {Ncs}}{3},\frac{{Nzc} - {Ncs}}{2}} \right\rbrack},}}}$

where, in the condition, the Ncs is the first Ncs, and the Nzc is alength of a ZC sequence;

if the du_(HT) value of at least one ZC sequence in the selected ZCsequence group does not meet the condition, reselect a ZC sequence groupaccording to the cell type and the first Ncs; and

if the du_(HT) values of the ZC sequences in the selected ZC sequencegroup all meet the condition, send the selected ZC sequence group to thesetting unit 702 and the sending unit 703.

Optionally, corresponding to the method embodiment shown in FIG. 4, thedetecting unit 704 is further configured to:

detect a primary peak value in the valid peak values in the fivedetection windows of each ZC sequence in the ZC sequence group;

determine a search window for a secondary peak value in the valid peakvalues according to a detection window in which the primary peak valueis located;

detect the secondary peak value in the search window for the secondarypeak value, and determine an RTD estimation window according to acombination relation between the detection window in which the primarypeak value is located and a detection window in which the secondary peakvalue is located; and

determine the estimated value of the RTD according to a position of thevalid peak value in the RTD estimation window.

Optionally, corresponding to the method embodiment shown in FIG. 5, thesetting unit 702 is further configured to:

determine start positions of the N detection windows of the i^(th) ZCsequence according to the du_(HT) value of the i^(th) ZC sequence in theZC sequence group as follows:

a start position of the detection window {circle around (1)} is 0;

a start position of the detection window {circle around (2)} ismod(du_(HT), Nzc);

a start position of the detection window {circle around (3)} ismod(−du_(HT), Nzc);

a start position of the detection window {circle around (4)} ismod(2*du_(HT), Nzc);

a start position of the detection window {circle around (5)} ismod(−2*du_(HT), Nzc);

a start position of the detection window {circle around (6)} ismod(3*du_(HT), Nzc);

a start position of the detection window {circle around (7)} ismod(−3*du_(HT), Nzc); and

others can be so deduced;

where mod(du_(HT), Nzc) means du_(HT) mod Nzc, and Nzc is a length ofthe i^(th) ZC sequence; and

set the N detection windows of the i^(th) ZC sequence according to thestart positions of the N detection windows of the i^(th) ZC sequence anda preset size of a detection window.

The N detection windows {circle around (1)}, {circle around (2)},{circle around (3)}, {circle around (4)} and {circle around (5)} . . .of the ZC sequence respectively correspond to frequency deviations 0,−Δf_(RA), +Δf_(RA), −2Δf_(RA), +2Δf_(RA), −3Δf_(RA) and +3Δf_(RA), . . ..

The detecting unit 704 is further configured to:

determine an RTD estimation window according to a detection window inwhich the valid peak value is located; and

if the detection window of the ZC sequence in which the valid peak valueis located does not overlap with other detection windows of the ZCsequence, randomly select one from the detection windows in which thevalid peak value is located as the RTD estimation window; or,

if the detection window of the ZC sequence in which the valid peak valueis located overlaps with other detection windows of the ZC sequence, butat least one valid peak value appears in a non-overlap, determine adetection window in which the at least one valid peak value is locatedas the RTD estimation window; or

if the detection window of the ZC sequence in which the valid peak valueis located overlaps with other detection windows of the ZC sequence, andthe valid peak value appears in an overlap, determine that no randomaccess signal is detected in the detection window in which the validpeak value is located; or perform frequency deviation processing on therandom access signal according to frequency deviations of two detectionwindows in which a primary peak value of the valid peak values islocated to obtain a new valid peak value, and determine the frequencydeviation and the RTD estimation window according to the new valid peakvalue; and

determine the estimated value of the RTD according to a position of thevalid peak value in the RTD estimation window.

Relevant descriptions of other detection windows in the ZC sequence areconsistent with those in step 507.

Optionally, the detecting unit 704 is further configured to:

estimate the frequency deviation according to a detection window inwhich the valid peak value is located.

For the estimating the frequency deviation according to a detectionwindow in which the valid peak value is located, refer to step 206.

It should be noted that the selecting unit 701, the setting unit 702,the sending unit 703, the receiving unit 704, and the detecting unit 705may all be a central processing unit (CPU), a digital signal processor,or other processors.

The apparatus for processing very-high-speed random access provided bythe foregoing embodiment solves a problem that an RTD of a random accesssignal cannot be correctly detected in a very-high-speed scenario,ensures that a user equipment moving at a very high speed can correctlyadjust a TA value according to a detected RTD, and therefore correctlyadjusts message sending timing, so that the user equipment in avery-high-speed scenario can normally access a network, therebyimproving access performance of the network.

A system for processing very-high-speed random access provided by theembodiment includes the apparatus for processing very-high-speed randomaccess shown in FIG. 7.

Persons of ordinary skill in the art may understand that all or a partof the steps of the foregoing method embodiments may be implemented by aprogram instructing relevant hardware. The program may be stored in acomputer readable storage medium. When the program runs, the steps ofthe foregoing method embodiments are performed. The storage medium mayinclude any medium capable of storing program code, such as a read-onlymemory (ROM), a random access memory (RAM), a magnetic disk, or anoptical disc.

Finally, it should be noted that the foregoing embodiments are merelyintended for describing the technical solutions of the present inventionrather than limiting the present invention. Although the presentinvention is described in detail with reference to the foregoingembodiments, persons of ordinary skill in the art should understand thatthey may still make modifications to the technical solutions describedin the foregoing embodiments, or make equivalent replacements to sometechnical features thereof, as long as such modifications orreplacements do not cause the essence of corresponding technicalsolutions to depart from the spirit and scope of the technical solutionsof the embodiments of the present invention.

1. A method for processing very-high-speed random access, comprising:selecting, by a base station, a Zadoff-Chu (ZC) sequence group accordingto a cell type and a first cyclic shift parameter, wherein the ZCsequence group comprises M ZC sequences, and a du_(HT) value of a j^(th)ZC sequence in the ZC sequence group meets a condition${{du}_{HT}} \in {\left\lbrack {{Ncs},\frac{{Nzc} - {Ncs}}{4}} \right\rbrack\bigcup{\quad{{\left\lbrack {\frac{{Nzc} + {Ncs}}{4},\frac{{Nzc} - {Ncs}}{3}} \right\rbrack\bigcup\left\lbrack {\frac{{Nzc} + {Ncs}}{3},\frac{{Nzc} - {Ncs}}{2}} \right\rbrack},}}}$wherein Ncs is the first cyclic shift parameter, Nzc is the length ofthe j^(th) ZC sequence, and j is an integer out of integers from 1 to M;and indicating, by the base station, the cell type and the ZC sequencegroup to a user equipment (UE).
 2. The method according to claim 1,wherein the method further comprises: setting N detection windows foreach ZC sequence in the ZC sequence group, wherein N≥5.
 3. The methodaccording to claim 2, wherein the method further comprises: receiving arandom access signal from the UE, and obtaining a random access sequencefrom the random access signal; and performing correlation processing onthe random access sequence with each ZC sequence in the ZC sequencegroup, detecting a valid peak value in the N detection windows of eachZC sequence, and determining an estimated value of a round trip delay(RTD) according to the valid peak value.
 4. The method according toclaim 3, wherein setting the N detection windows for the j^(th) ZCsequence in the ZC sequence group comprises: obtaining a du_(HT) valueof the j^(th)-ZC sequence in the ZC sequence group; determining startpositions of the N detection windows of the j^(th)-ZC sequence accordingto the du_(HT) value of the j^(th)-ZC sequence; and setting the Ndetection windows of the j^(th)-ZC sequence according to the startpositions of the N detection windows of the j^(th)-ZC sequence and apreset detection window size; wherein the du_(HT) value of the j^(th)-ZCsequence corresponds to a shift of a mirror image peak in a power delayprofile (PDP) of the j^(th)-ZC sequence relative to the RTD when afrequency deviation is ${\pm \frac{1}{T_{SEQ}}},$ wherein T_(SEQ) is atime duration occupied by the j^(th)-ZC sequence.
 5. The methodaccording to claim 3, wherein, when a frequency deviation range ofvery-high-speed random access is$\left\lbrack {{- \frac{5*\Delta \; f_{RA}}{2}},\frac{5*\Delta \; f_{RA}}{2}} \right\rbrack$in which Δf_(RA) represents a subcarrier spacing of a random accesschannel, setting the N detection windows for a j^(th) ZC sequence in theZC sequence group comprises: obtaining a du_(HT) value of the j^(th)-ZCsequence in the ZC sequence group; and setting five detection windows ofthe j^(th)-ZC sequence according to the du_(HT) value of the j^(th)-ZCsequence; wherein the du_(HT) value of the j^(th)-ZC sequencecorresponds to a shift of a mirror image peak in a power delay profile(PDP) of the j^(th)-ZC sequence relative to the RTD when a frequencydeviation is ${\pm \frac{1}{T_{SEQ}}},$ wherein T_(SEQ) is a timeduration occupied by the j^(th)-ZC sequence.
 6. The method according toclaim 5, wherein setting the five detection windows of the j^(th)-ZCsequence according to the du_(HT) value of the j^(th)-ZC sequencecomprises: obtaining start positions of the five detection windows ofthe j^(th)-ZC sequence according to the du_(HT) value of the j^(th)-ZCsequence, wherein the five detection windows comprise a detection window{circle around (1)}, a detection window {circle around (2)}, a detectionwindow {circle around (3)}, a detection window {circle around (4)} and adetection window {circle around (5)}, wherein a start position of thedetection window {circle around (1)} is 0, wherein a start position ofthe detection window {circle around (2)} is mod(du_(HT), Nzc), wherein astart position of the detection window {circle around (3)} ismod(−du_(HT), Nzc), wherein a start position of the detection window{circle around (4)} is mod(−2*du_(HT), Nzc), wherein a start position ofthe detection window {circle around (5)} is mod(−2*du_(HT), Nzc); andsetting the five detection windows of the j^(th)-ZC sequence accordingto the start positions of the five detection windows and a presetdetection window size.
 7. The method according to claim 3, whereindetecting the valid peak value in the N detection windows of each ZCsequence and determining an estimated value of a round trip delay (RTD)according to the valid peak value comprises: detecting a primary peakvalue from valid peak values in the N detection windows of each ZCsequence; determining a search window for a secondary peak value in thevalid peak values according to a detection window in which the primarypeak value is located; detecting the secondary peak value in the searchwindow for the secondary peak value, and determining an RTD estimationwindow according to a combination relation between the detection windowin which the primary peak value is located and a detection window inwhich the secondary peak value is located; and determining the estimatedvalue of the RTD according to a position of the valid peak value in theRTD estimation window.
 8. The method according to claim 3, whereindetermining the estimated value of the RTD according to the valid peakvalue comprises: determining an RTD estimation window according to adetection window in which the valid peak value is located; anddetermining the estimated value of the RTD according to a position ofthe valid peak value in the RTD estimation window.
 9. The methodaccording to claim 1, wherein the cell type indicates whether a cell isan unrestricted cell or a restricted cell.
 10. The method according toclaim 1, wherein the method further comprises: when the du_(HT) value ofat least one ZC sequence in the ZC sequence group does not meet thecondition, reselecting another ZC sequence group according to the celltype and the first cyclic shift parameter.
 11. An apparatus forprocessing very-high-speed random access, comprising: a processor; and anon-transitory computer-storage medium having processor-executableinstructions stored thereon; wherein the processor-executableinstructions, when executed by the processor, facilitate: selecting aZadoff-Chu (ZC) sequence group according to a cell type and a firstcyclic shift parameter, wherein the ZC sequence group comprises M ZCsequences, and a du_(HT) value of a j^(th) ZC sequence in the ZCsequence group meets a condition${{du}_{HT}} \in {\left\lbrack {{Ncs},\frac{{Nzc} - {Ncs}}{4}} \right\rbrack\bigcup{\quad{{\left\lbrack {\frac{{Nzc} + {Ncs}}{4},\frac{{Nzc} - {Ncs}}{3}} \right\rbrack\bigcup\left\lbrack {\frac{{Nzc} + {Ncs}}{3},\frac{{Nzc} - {Ncs}}{2}} \right\rbrack},}}}$wherein Ncs is the first cyclic shift parameter, Nzc is the length ofthe j^(th) ZC sequence, and j is an integer out of integers from 1 to M;and indicating the cell type and the ZC sequence group to a userequipment (UE).
 12. The apparatus according to claim 11, wherein theprocessor-executable instructions, when executed by the processor,further facilitate: setting N detection windows for each ZC sequence inthe ZC sequence group, wherein N≥5.
 13. The apparatus according to claim12, wherein the processor-executable instructions, when executed by theprocessor, further facilitate: receiving a random access signal sent bythe UE and obtaining a random access sequence from the random accesssignal; and performing correlation processing on the random accesssequence with each ZC sequence in the ZC sequence group, detecting avalid peak value in the N detection windows for each ZC sequence, anddetermining an estimated value of a round trip delay (RTD) according tothe valid peak value.
 14. The apparatus according to claim 13, whereinthe processor-executable instructions, when executed by the processor,further facilitate: obtaining a du_(HT) value of the j^(th) ZC sequencein the ZC sequence group; determining start positions of the N detectionwindows of the j^(th)-ZC sequence according to the du_(HT) value of thej^(th)-ZC sequence; and setting the N detection windows of the j^(th)-ZCsequence according to the start positions of the N detection windows ofthe j^(th)-ZC sequence and a preset detection window size of a detectionwindow; wherein the du_(HT) value of the j^(th)-ZC sequence correspondsto a shift of a mirror image peak in a power delay profile (PDP) of thej^(th)-ZC sequence relative to the RTD when a frequency deviation is${\pm \frac{1}{T_{SEQ}}},$ wherein T_(SEQ) is a time duration occupiedby the j^(th)-ZC sequence.
 15. The apparatus according to claim 13,wherein the processor-executable instructions, when executed by theprocessor, further facilitate; when a frequency deviation range ofvery-high-speed random access is$\left\lbrack {{- \frac{5*\Delta \; f_{RA}}{2}},\frac{5*\Delta \; f_{RA}}{2}} \right\rbrack$obtaining a du_(HT) value of the j^(th) ZC sequence in the ZC sequencegroup; and setting five detection windows of the j^(th)-ZC sequenceaccording to the T value of the j^(th)-ZC sequence; wherein the du_(HT)value of the j^(th)-ZC sequence corresponds to a shift of a mirror imagepeak in a power delay profile (PDP) of the j^(th)-ZC sequence relativeto the RTD when a frequency deviation is ${\pm \frac{1}{T_{SEQ}}},$wherein T_(SEQ) is a time duration occupied by the j^(th)-ZC sequence.16. The apparatus according to claim 15, wherein the cell type indicateswhether a cell is an unrestricted cell or a restricted cell.
 17. Theapparatus according to claim 11, wherein the processor-executableinstructions, when executed by the processor, further facilitate: whenthe du_(HT) value of at least one ZC sequence in the ZC sequence groupdoes not meet the condition, reselecting another ZC sequence groupaccording to the cell type and the first cyclic shift parameter. 18.(canceled)
 19. A non-transitory computer readable medium comprisingprocessor-executable instructions stored thereon, wherein theprocessor-executable instructions include: instructions for selecting aZadoff-Chu (ZC) sequence group according to a cell type and a firstcyclic shift parameter, wherein the ZC sequence group comprises M ZCsequences, and a du_(HT) value of a j^(th) ZC sequence in the ZCsequence group meets a condition${{du}_{HT}} \in {\left\lbrack {{Ncs},\frac{{Nzc} - {Ncs}}{4}} \right\rbrack\bigcup{\quad{{\left\lbrack {\frac{{Nzc} + {Ncs}}{4},\frac{{Nzc} - {Ncs}}{3}} \right\rbrack\bigcup\left\lbrack {\frac{{Nzc} + {Ncs}}{3},\frac{{Nzc} - {Ncs}}{2}} \right\rbrack},}}}$wherein Ncs is the first cyclic shift parameter, Nzc is the length ofthe j^(th) ZC sequence, and j is an integer out of integers from 1 to M;and instructions for indicating the cell type and the ZC sequence groupto a user equipment (UE).
 20. (canceled)
 21. The non-transitory computerreadable medium according to claim 19, wherein the cell type indicateswhether a cell is an unrestricted cell or a restricted cell.
 22. Thenon-transitory computer readable medium according to claim 19, whereinthe processor-executable instructions further include: instructions forreselecting, when the du_(HT) value of at least one ZC sequence in theZC sequence group does not meet the condition, another ZC sequence groupaccording to the cell type and the first cyclic shift parameter.